From the testing I have done the lack of peers seems related to Windows 10. I can't get connected to more than 2 peers even with adding many manually.
I have noticed similar behavior with other coins on this OS as well with lack of peers and have not found a solution. (even with firewall disabled on machine)
When I do the same thing on Win 8.1 I have no problems getting peers with the same config, TCP and UDP port 47286 forwarded.
I run Windows 10 on all my machines, except one that runs Ubuntu Linux. Seems, like an issue with Windows 10.
I have 4 peers now on Win10. I don't think the node discovery works as well on this OS and the manual additions do not have an immediate impact like on 8.1.